there are several ways to do this.
1. (the right way) is to move these variables into a 3rd unit but that's only if there are several and they may grow into an object.
2: declare them in the interface section of the file they live in.
3: just add then into the "public" section of the form's "TForm " def
however you do it, the other unit will need to "uses" this form (which form1 proably already does).
expamle with var living in the pubic
implementation
uses form2; // to access "myfrm2"
...
if myfrm2.var1 > myfrm2.var2 then ...
..